VeryDOC Knowledge Base

VeryDOC PDF Password Remover has command line version for users to call it by script easily. In this article, how to remove PDF password in script with this tool can be shown to you in details as you expect.

If GUI interface of this tool could not suit you, maybe CMD version can make you simply achieve decryption of removing PDF passwords through command lines and parameters. Here is CMD example for you to refer to below, and I hope this tool can bring you fun:

Step1. Download

Please download package of VeryDOC PDF Password Remover directly, and then, after you extract its content to your computer, executive file “pdfdecrypt.exe” could be in your computer for later application.

Step2. Run cmd.exe in Windows systems

After extraction, you can run cmd.exe in your computer, so, targeting command prompt window, which is running environment of command lines, could pop on screen.

Step3. Accomplish removing PDF passwords

Firstly, please get familiar with usage:

pdfdecrypt.exe –i <input PDF> –o <output PDF> [options]

Note: If you do not specify the -o parameter, the default output file will overwrite the input PDF file.

where [options] can be following parameters with strings except “-i, –o”

• -i [pdf file name] : decrypt PDF filename or directory
• -o [pdf file name]: PDF file will be generated
• -u <string>: input user password
• -w <string>: input owner password
• -v: view the decrypted PDF file after decryption
• -l [log file name]: specify log file for output message

Then, you can refer to the following examples to use parameters to achieve process you want:

pdfdecrypt.exe -i C:\sample.pdf -o C:\decrypt.pdf -w owner -u user -l C:\error.log

pdfdecrypt.exe -i C:\sample.pdf -w "owner" -u "user"

pdfdecrypt.exe -i C:\sample.pdf -o C:\out1.pdf -w "owner"

pdfdecrypt.exe -i C:\sample.pdf -o C:\out2.pdf -u "user"

pdfdecrypt.exe -i C:\pdfdir\ -o D:\ -l C:\error3.log

In addition, if you need to batch remove passwords of PDF files, please type correct commands line as above in a BAT file, then, after you save them and close this BAT file and double-click its icon, you can get targeting PDF files without passwords in destination folder.

Here is the end of this article, I hope simple method to remove PDF files passwords singly or in batches satisfy your needs from the easy-to-operate command line examples mentioned above. If you have any questions, please feel free to leave your comments here. To own this tool for good, just choose full version of VeryDOC PDF Password Remover.

This article aims showing what PDF passwords can be or can not be removed during removing PDF passwords with restrictions with VeryDOC PDF Password Remover.

Like you can tell, VeryDOC PDF Password Remover supports instantly removing PDF owner passwords with restrictions, as well as open passwords known by users previous. However, not any kinds of encrypted PDF passwords could be supported to remove, as well as specified PDF files. So, in the following paragraphs, what can be of removing or not by this tool would be shown in the following description:

What VeryDOC PDF Password Remover support based on PDF type and encryption modes:

• For PDF type - support up to PDF version 1.8, including Acrobat 9.0 PDF files
• For encryption level - remove 40 bits and 128 bits RC4 encryption owner passwords
• For encryption mode – 128 bits AES - remove AES encryption owner passwords

What VeryDOC PDF Password Remover does not support:

• PDF files which are not what software itself supports
• PDF passwords set without what I mentioned in supported encryption modes
• PDF passwords encrypted beyond mainstream encryption of PDF
• PDF passwords encrypted with specific Adobe Plug-ins
• PDF passwords which are set by not Adobe Corporation

By now, maybe you need to experience this tool, so, it is easy for you to try VeryDOC PDF Password Remover here. And then, you wonder what encryption modes Adobe Corporation have designed for us, then, please read the following extension knowledge:

Basically, three main ways can be used to encrypt a PDF file by Adobe Corporation:

• Password encryption

Password encryption is a technology, which depends on a shared password by publisher and recipients. If you do not understand this, here is an example:

Suppose the publisher use a string like “No1Kn0w$” to encrypt PDF, and then, the recipients need to use the same string to decrypt it.  However, to prevent this encryption from being attacked by brute force, as well as guessing of simple passwords, please make sure complex passwords, e.g., like song lyrics, poetry, and other long phrases as source material of PDF passwords to set.

• Public Key Infrastructure (PKI) encryption

PKI encryption, which is a further technology, help you set greater protection by using additional cryptography and digital certificates.

For instance, while encrypting, the publisher’s computer randomly generates a symmetric key(up to AES256), and encrypts that key to each recipient’s asymmetric public key to include in the document with the symmetric key encrypted content.  In return, the recipient computer uses their own private key to decrypt the symmetric key, and then decrypt the document.  When the private key is stored on a token, e.g. USB, etc., it can provide two factor security, which are requiring the token and any PIN codes to unlock this token.

• Rights Management

Rights Management, which has been developed to provide integration into enterprise authentication (AuthN) and authorization (AuthZ) infrastructure without requiring PKI, could be used in those same directories to read in groups of users.

With this technology, rights management “policy”, which is an easily reusable way to protect documents, can be created by administrators. In this kind of policy, how to open the document, what you can do with the document and what can be tracked based on what users have done with the document, can be set professionally and easily as you wish. The publisher then selects the policy to protect a document. In addition to username/password types of authentication, the server can also support Kerberos single sign on (SSO),PKI authentication (which is different than PKI encryption above), OTP, and other custom methods.  With the professional help of this technology, document usage can be expired, revoked, version controlled, watermarked, and audited. Thus, it is great to use this brilliant technology for communities of users. In addition, this technology can be compatible with popular smart phones and tablet devices.

At last, what are important is that, three encryption methods mentioned above, are all possible to restrict printing, clipboard, and modification as usual.

In the end, welcome to share your problems and questions with comments here, if you encounter them during removing PDF passwords with VeryDOC PDF Password Remover.

Some users get questions when they use VeryDOC PDF Password Remover to remove PDF password instantly: can this software help us remove open password? If so, why does this utility not remove PDF open password all the time? And this article would like to explain these phenomenon for you.

Usually, VeryDOC PDF Password Remover can remove PDF master passwords with restrictions singly or in batches as you expect. However, in some specified condition, this GUI tool also allow you to remove open passwords singly or in batches, and this condition is that you have already known PDF open passwords, which you can understand as you set those PDF open passwords. And of course, the processing based on this smarter application is the same as removing PDF master passwords with restrictions, and if you would like to review relevant details, 2 situations can be described in the following paragraphs, after you get trial version of VeryDOC PDF Password Remover:

If it is first time for you to remove PDF open password

1. Open GUI interface on screen

2. Select right open and owner password protected PDF file in pop dialog box after you click Open PDF(s) > click Open

3. After selected PDF is added, program gives you another dialog box for you to select destination folder, and with one click on Save

4. Along with successful setting in destination folder, program provides a dialog box, where program requires you to input open password and master password in related edit-boxes, and after that, one click on Ok, enables removing PDF open and owner passwords one time successfully, which can be signaled from successful info in processing form

And the following snapshots bring you more details:

Note: when you input PDF password in pop window, there is no need to type owner password as typing open password, for this tool enables direct and instant removing of PDF master passwords.

If you removed PDF open password before

After you get selected PDF open password removed as above, suppose you forget removing this PDF open password and owner password in the future, and one day, you take this PDF back to remove these PDF passwords again, then, this password remover will not give you pop window as shown in first snapshot above to remind you of typing open password, oppositely, this tool directly remove all passwords and restrictions than you expect, for it has strong memory of what it has done before, as well as knowing open password of PDF by you. And that is the reason why some users can directly remove PDF open passwords, not as beginners, who use this tool in the first time.

After my explanation, I hope this article could be of a little help, and if you still have questions about these problems based on removing PDF open passwords and master passwords or other issues, welcome to leave your comments here.